Scaling down the keyframes
In the animation editor, position the 2D cursor to the frame you want to use as the "origin" for your scale operation (probably the first frame of the animation) and set the pivot point to "2D Cursor".

Select the keyframes you want to scale. Press s to scale, x to scale on the x-axis (time), then type 66, and press Enter. Then press s, x, then type 110/ to scale by 1/110, and press Enter to apply. This will scale your keyframes' timekeys by a factor of 66/110.

The keyframes will probably not align perfectly with entire frames. Blender's interpolation system can handle this just fine. If you want, you can snap them to entire frames by pressing Shift+S and choosing "Nearest Frame".